1. Field of the Invention
This invention relates to magnetic data storage disk manufacturing and in particular to an apertured disk, a plug for use with the disk and a disk carrier, the plug preventing passage of sputtered magnetic material through the aperture during disk manufacture.
2. Material Art
The manufacture of magnetic disks is broadly described in U.S. Pat. 4,634,512, an invention of R. Allen and Tu Chen. In that patent and U.S. Pat. 4,595,481 the use of multi-part plugs is disclosed for plugging the disk operation during disk manufacture. The plug is of multi-piece construction where two main body parts are pushed together through the disk aperture from opposite sides of the disks. The plug body parts are held by a spring (4,595,481) or by a magnet in one of the body parts (4,634,512). The disk carrier has a series of apertures which are sized and grooved to receive a number of apertured disk blanks for plasma application of magnetic media, such as cobalt-nickel-chromium alloy or other known alloys, simultaneous on both sides of the disk and typically by a plasma sputtering operation. Each disk plug main body part has a knob extending therefrom so that the disk and overall plug can be inserted and removed from the carrier by hand or robot.
As seen in U.S. Pat. No. 4,735,540, also an invention of Messrs. Allen and Tu Chen, a robot may be employed to remove a blank disk from a cassette by a pair of robot arms with robot fingers grasping the opposed plug knobs of a previously inserted two-part plug, transporting it to the carrier for insertion therein, inserting the plugged disk into the carrier, and after the magnetic media is applied to the plugged disks in the carrier, removing the disk and plug together from the carrier, transporting the assembly to a receiving cassette and unplugging the plug halves from the finished disk after it has been inserted into the finished disk cassettes.
While the above-described carrier, two-part plug and robotic system has been successfully used in magnetic media disk commercial production, it has been found that the plugging and unplugging action incident to the use of the two-part plugs generates minute (typically from about 0.1, to about 10 micron) particles which can become deposited on the disk and cause magnetic defects on the disk. Further, the plug/unplug action takes a considerable amount of time thereby increasing the manufacturing cycle time, decreasing the productivity of the very expensive plasma sputtering system and increasing manufacturing time and costs. Further, a fairly complicated robotic system was necessary to remove a disk blank from a cassette before plugging could take place with plug parts entry from both sides of the disk involving two sets of robotic arms working in unison. All of these substantial mechanical movements also will generate additional minute particles and thus more potential magnetic defects in the finished disks, all with an impact on productivity and a resultant greater cost of manufacture.